Pressure fluid supply system



Aug. 19, 1952 WALKER ETAL PRESSURE FLUID SUPPLY SYSTEM Original Filed May 3, 1945 FIGI D wam' gg Patented Aug. 19; 1952 I Daniel Norman Walker, Olton, Birmingham, and y Robert Edward Ingham, West Mersea, England, assignors to-Power Jets (Research and Development) Limited, London, England, a British company Original application May 3, 1945,":Serial "No 591,750. Divided and; this application February 20, 1951, Serial No. 211,892. In'Great Britain April 16, 1945 Thisinvention relates to' pressure fluid supply s'y'stems'fand in particularto 'systems in which it is required to supply fuel for example to an aero engineunder substantial pressure. Some classes of engine are dependent upon a pressure fuel supplyjfor their operation, for example engines of the'gas turbine class. 'Such engines comprise a compressor driven by a turbine mounted co-axial- :lyon the same shaft, the air drawn in by'the com- .pre'ssor,'b'eing delivered to 'a' plurality of combustion'chambers into which'fuel is injected "and the mixture ignited, the hot gasesthen being led to the turbine, thus driving it, and" being subsequently emitted to atmosphere. In the interest of reliability of operation it may be considered desirable to provide a system such thatv if a pump failure should occur the engine is not to be out of action and it is also found desirable at least in connection with gas turbine engines to provide a fuel system such that for starting purposes a rate of supply is available (at. comparatively low pressure) which would require a larger capacity pump than is necessary'for normal running after starting. The present invention seeks to provide a pressure fluid supply system in which dual pumps are afforded which meet the requirement of reliability andin which a comparatively large capacity is available for example to meet the requirements of'starting a gas turbine engine. It is assumed in the following description that the pumps are mechanically driven by the engineitself although .there may be cases where they are independently driven. 1

According to the invention a pressure fluid supply system including a pair of pumping elements for continuous operation, acommon suction conduit and a common discharge conduit having suction and discharge branches respectively connecting'the pumping elements in parallel for parallel suction and parallel discharge flows, non-return fvalves in both the discharge branches for'permitting flow only in the direction of discharge, a main by-pass conduit connecting the discharge branch of one of the pumping elements from a point between the one pumping element and its non-return valve to the common suction conduit,

lClaim. (01, 103-11) I drawings'in which:

conduit when the discharge pressure of the other pumpingelement' is below a predetermined value to permit said pairj'of Dumping elements to pump in parallel and discharge fluid to the common discharge conduit and 'the valve means being actuated by the pressure fluid when the discharge pressure of the other pumping element is above the predetermined value to open the by-pas's conduit tO permit the; one pumping element; to-discharge fli id' tosa id common suction whilst the other pumping element continues "to, discharge fluid to the common discharge, a control valve and a secondary .discharge branch inthe'by-pass conduit between said pressure actuated flow control valve means and thecommon suction, the controlvalve being adaptedto control the flow of the one pumping element when discharging the The invention will be better understood from I the following description of one form of embodiment of the inventionwhichis given by way of example with reference" to the accompanying Fig. 1v is a diagrammatic representation of a system accordingito th'e invention with the pressure actuated fluid flowjcontrol "valve means closed;

Fig. 2 is a similar representation of the same system with the pressure actuated fluid flow control valve means open.

Referring to the drawings, the system according to the invention comprises two pumps A, B, the pair delivering liquid under pressure, the

liquid being led from a source of supply through a main suction pipe connection I. f

A branch pipe 2" is connected to' pipe I and leads t5 the suction side of pump B, the delivery side of this pump being connected through a .pipe 3 to a non-return valve 1 and thence by a pipe 6 to a pipe [2 for delivery of the fluid to the ap-.

of a pressure*actuatedfluid flow control valve means consisting of a casing l5 enclosingsaid chamber l6 in which a piston valve I'3 slides against the resistance of a spring 14. r

The chamber-,lfifcan communicate through a port I8 and a-pipe lflback to the main suction pipe I, the pipes 4 and ID constituting a main by-pass conduit. The chamber [6 is connected' by an opening 32 to a pipe in communication" piston valve [3 to provide a passage for the fluid passing from the pump B when the lateral-opening I1 is uncovered by the piston valvel3.-

Fig. 1 represents the condition of the system when for example it is desired to start a gas turbine engine in which combustion is effected by means of burners (notshown) .to which pipe I2 is connected for the delivery ofiuel. The spring l4 isdesignedto'yield at a certain predetermined spring M on the piston valve 13 may operate to close the pressure actuated flow control valve means when this is requiredto remain open.

' According to the invention, "the -pu'mp B is adapted to be capable of use for other purposes when pump A is delivering the whole load. With this object in'view, a branch pipe 22 may be connected to pipe 10 (Fig. 2) and a shut-off valve 31 in'ser-te'd'into pipe Ill so that when communication with pipe 1 is cut oii, pump B can be used to 'deliver'fluid under pressure to any other purpose desired.

This arrangement is an advantageous one for example in: the application of the system as a pressure of the fluid dis'ch'arged'by'the pump vA s0 that} when the pressure of'ithe fuel. delivered is lessthan this value, the piston valve I3 is closed and .there is nocommunic'ation between ports I1 and '18, but-when .this pressure is exceeded, then the piston valve is moved against-the spring I l andby.meansoiithe"annular groove l'9,.ports I1 andliB can then communicate with one another.

Forstarting conditions, the pressure actuated flow .control valve means is closed as lshownin Fig. l and. pumps A and B are in this case operating in parallel. indicated bythe arrows which'showthe path-of the .fuel, pump 3 is supplying -fuel'via pipe 3, non-return valve 1 and pipe 6, while pump A delivers fuel through pipe I I, non-return valve 8 and pipe I 2 to the burners. The pressure of the fuel delivered increases until it reachesfthe predetermined pressure and when thisvalue is reached the-piston valve I3 moves against spring [4, thusputting ports 17 and I8 and consequently-pipes 4 and'lfl in' communication with one another, as shown in Fig, 2. In this condition, as shown by the arrows, pump B circulates fuel idly and is operating (in-substantially no load while 'pumphcontinues todeliver and is alone responsible.forfdelivering substantially all the fuel required at the desired'pressure- The nonreturn valve 7 prevents pump A from delivering fuelw backto suction. via the pressure actuated flow control valve means] If pump'A fails, the pressure inits delivery line I 1 drops andthe piston valve l3 in the pressure actuated flow control valve then moves back to the position of Fig. 1 thus cuttingoli communication between the delivery side of pump 13 and pipe I. As shown by: the arrows, pump B then delivers fuel, through pipe 3, non return valve"! and pipe 6 to the burners and is then itself responsible for delivering all the fuel-at the required-pressure.

. If pump B fails while A is operating under load, then the system remains otherwise unaffected and pump A continues to deliver.

As theflow through a failed pump may in some cases be relatively small, a bleed .line 20 is provided in the piston valve I3 of the'pressure actuated flow control valve means inorder to promote a rapid'changeover. A lead 9 to drain is also provided in the said valve for the purposejof permitting leakagethrough the piston valve; l3 to drain back to source; and thus prevent any possibility of such leakage building up a pressure which together with the force exerted by the iuel system-for a gas turbine engine. In such an enginepair-is drawn in by a compressor, the

compressed air 'isinjected with fuel and the mixture is ignited, the gaseous products then being used to drive a turbine which itself drives the compressor, and the exhaust gases aresubsequentlyl ejected into the atmosphere: In -one form or. such engine the exhaust gases after leaving the turbine maybe subjected to'ai proc'ess'lmown as i'fi'eheat i. "e. are giveiii'a; further 'fuel lines non and subjected to additional combu'stiohibefore being finally discharge'djmtotheatmos here. ln'such a iorm'oflgas t irbin'e engine, puin'ijA may deliver through {pipe j l 2',' the main "fuel? sup ply. to a series ofV-burnersrorthe main comb'ustion duringnorrnal runni g a "pu'rnpfB can be usedl'to de'liver 'fueltlirniigh'pi e' 22l'to onor me e. burners located" downstream or the'tu'rbine in. the case where the 'hot.'exhaiistfgases "aresubjeot to reheat.

z I The pressureactua'ted'flow cdntrorvalvemeans is forthis reasonedapted..to'ibe pressurebal an'eed so that" any jbaclepres'siiife ofIthis relieat fuel through-opening; IB'tvill haveno'efiect on the movement of pistonl'SiaIid thus onthe opera: tion of the changeover valve. I V

The shut-ofi valve 3 operated by' any means for example, it'may. be manually operated or it may be electrically operated. f

Thepumps .A and B'fare of the positive displacement, typefandi they may" begear" pilmps actually driven from the engine "shaaro'rexam: ple in the case of. a gas turbinf aero' engine. Relief valves maybe provided in'associatio'n with any] part of u the system .wherffthe possibility of excess pressure ma arise ne -the. non-return valve may have associated with them'any suitable signalling device" to give an indieatio'n 'of the operative condition of the systemat anyi one time.

. Although. the above descriptien ha beengiv'en with reference to two pumps only, 'it is tobe understood that thefsyste'm may contain more than .two pumps so thatwhen starting'twd or more than two pumps may-be in parallel and during normal running one-pump or 'more than one pump'may be idle. Ihe'systern may also'be applied: to other purpeses than. to gas-turbine orhther engines.

' TheIp-ressure actuated fiow contro l valve means may -be provided withia me'ansisuch asa spring loaded -lai'i le linkage f-t-o give mevaw a snap actionso-that it is hel'diinoneor otherof its positions until there'is a. sub'stantial change of conditions, flutter of the valve thus being avoided. nlternatively Ithe valve m'ay. be 1 operated emancall yfor example by a solenoid-ina circuit which is itselfafiectedby the operating} conditions.

This application is a division of eapplication Serial N m r 59 fil d: Ma 3 a t joint application of Daniel N. Walker and Robert E. Ingham, and subsequently changed to a sole application of Daniel N. Walker.

We claim:

A pressure fluid supply system including a pair of pumping elements for continuous operation, a common suction conduit and a common discharge having suction and discharge branches respectively connecting said pumping elements in parallel for parallel suction and parallel discharge flows, non-return valves in both said discharge branches for permitting flow only in the direction of discharge, a main by-pass conduit connecting the said discharge branch of one of said pumping elements from a point between said one pumping element and to its non-return valve, to said common suction conduit, a pressure actuated flow control valve means in said by-pass conduit for controlling the flow therein, a pressure conduit connecting said discharge branch of said other pumping element from a point between said other pump- 20 ing element and its said non-return valve to said pressure actuated flow control valve means for supplying pressure fluid from said other pumping element to actuate said control valve, said control valve means being biassed to close the said by-pass conduit when the discharge pressure of said other pumping element is below a predetermined value to permit said pair of pumping elements to pump in parallel and discharge fluid to said common discharge conduit and said valve means bein actuated by said pressure fluid when said discharge pressure of said other pumping element is above said predetermined value to open said by-pass conduit to permit said one pumping element to discharge fluid to said common suction whilst said other pumping element continues to discharge fluid to said common discharge, a control valve and a secondary discharge branch in said by-pass conduit between said pressure actuated flow control valve means and said common suction, the control valve being adapted to control the flow of said one pumping element when discharging to said common suction conduit to permit flow only to said. common suction conduit when in one position and to permit flow only to said secondary discharge branch When in another position.

DANIEL NORMAN WALKER.

ROBERT EDWARD INGHAM. 7

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 655,037 Wheeler July 31, 1900 1,002,306 Perkins Sept. 5, 1911 1,148,054 Rosencrans July 27, 1915 2,085,982 Johnson July 6, 1937 2,173,578 Egersdorfer Sept. 19, 1939 2,218,565 Vickers Oct. 22, 1940 2,219,994 Jung Oct. 29, 1940 2,280,392 Herman Apr. 21, 1942 2,366,388 Crosby Jan. 2, 1945 2,367,452 Wheatley Jan. 16, 1945 FOREIGN PATENTS Number Country Date 663,396 Germany 1938 703,569 France 1931 

